This invention relates generally to ground-working disc implements and is particularly directed to an arrangement which allows for deflection of individual disc blades in a multi-disc harrow implement.
Discs used in tilling the soil are necessarily of relatively thin metal and include a sharp edge around the periphery thereof. In the normal course of operation, these discs impact obstructions in the field, such as rocks, which lie below the surface and remain unseen. Although typically made of a hard steel, such impact will inevitably result in the dulling or breaking of discs and frequently leads to damage to the disc support structure, i.e., the gang bolt upon which the discs are positioned. This, of course, necessitates equipment repair or replacement. Ideally, a disc mounting arrangement would provide for the stable tracking of the disc through the tilled soil while permitting the disc to be freely deflected upon impact with an obstruction.
The prior art discloses various approaches directed toward yieldable mountings for disc harrows. U.S. Pat. No. 2,253,391 to Ohlendorf discloses one such approach making use of resilient means in the form of washers positioned between the faces of the discs and facing spools positioned on a gang bolt. U.S. Pat. No. 2,275,791, issued in the name of the present inventor, discloses another approach in which yieldable biasing means hold the individual disc blades in a normal working position. When the disc blade impacts an obstruction in the field such as a rock, the force is transmitted to the biasing means which yields and therefore allows the individual disc blade to yield, thereby preventing structural damage to the disc blade. The biasing means is in the form of a donut-shaped spring in combination with interconnected wedge blocks. Another disc gang assembly is disclosed in U.S. Pat. No. 4,420,048 to Peterson. These and other approaches in the prior art have suffered from various shortcomings such as high complexity and associated excessive cost and have still not been able to completely eliminate the possibility of structural damage to a disc harrow upon impact with an obstruction in the field.
The present invention is intended to overcome the aforementioned limitations of the prior art by providing a disc mounting arrangement wherein the disc is insulated from direct impact with its associated disc mounting assembly which provides for the free deflection of the disc upon impact with an obstruction.